Methods 5 - Example with three methods

Purpose of this lesson: Programming ideas

Here is another variation of the program, this time using three methods. Altho there is no real need for these methods in such a small program, large programs are in fact composed of many small methods. It is the essential way that all code is structured.

Each of the user-defined method names, both in the call and the definition, is hilited.

Source code

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// File   : methods/KmToMilesMethods.java
// Purpose: Converts kilometers to miles using two methods.
// Author : Fred Swartz - placed in public domain
// Date   : 22 Apr 2006

import javax.swing.*;

public class KmToMilesMethods {
    //========================================================= constants
    private static final double MILES_PER_KILOMETER = 0.621;    

    //============================================================== main
    public static void main(String[] args) {
        double kms   = getDouble("Enter number of kilometers.");
        double miles = convertKmToMi(kms);
        displayString(kms + " kilometers is " + miles + " miles.");
    }

    //===================================================== convertKmToMi
    // Conversion method - kilometers to miles.
    private static double convertKmToMi(double kilometers) {
        double miles = kilometers * MILES_PER_KILOMETER;
        return miles;
    }

    //========================================================= getDouble
    // I/O convenience method to read a double value.
    private static double getDouble(String prompt) {
        String tempStr;
        tempStr = JOptionPane.showInputDialog(null, prompt);
        return Double.parseDouble(tempStr);
    }

    //===================================================== displayString
    // I/O convenience method to display a string in dialog box.
    private static void displayString(String output) {
        JOptionPane.showMessageDialog(null, output);
    }
}

Review Questions

[TODO]

Programming Problems

  1. Hammurabi 0